Recently, liquid crystal display, plasma display and organic EL used for personal computer, word processor, watch or electric calculator are frequently employed under severe conditions. Consequently, high durability is required to an optical film such as a polarization plate protecting film, an optical compensation film, a front filter for plasma display panel and a front film for organic EL panel. Therefore, it is demanded that the properties of them are not varied under the severe conditions, for example, the physical properties of the film are not varied by the use for a long period and superior in the in the uniformity.
It is important for the protecting film that the film has low optical anisotropy, the high transparency and is superior in the UV absorbing ability and the moisture barrier function to prevent lowering in the dimensional stability and the polarizing layer.
As the raw material of the optical compensation film, for example, norbonene, polycarbonate, polysulfone, poly(ether sulfone) and amorphous polyolefin are usable. Each of these polymer optical compensation films is usually pasted with the polarization plate for using in combination. Therefore, a shortcoming is posed that the cost rises since many sheets of the film are laminated. Furthermore, a problem of occurrence of inferior products caused by intrusion of air bubbles or foreign substances or formation of wrinkles on the occasion of the pasting is posed additionally to complication of the producing process.
Besides, the optical compensation film principally composed of cellulose resin can be pasted with the polarization plate in place of the polarization plate protecting film. Therefore, the production process of the liquid crystal can be shortened and the producing efficiency is raised by such the film, cf. Patent Documents 1 through 5, for example.
In Patent Document 6, for example, a technology is disclosed in which TAC film produced by a solution-casting method is employed as the support and a polymer layer is coated on the support and stretched together with the support at high temperature for giving a desired retarding property and pasted with a polarization plate. Hitherto, a problem is posed that ununiformity tends to be caused by uniformity of the stretching when the polymer layer is formed on the TAC film separately from the film producing process of the TAC film by the solution-casting method and stretched at the high temperature. Moreover, a problem is posed that the haze tends become higher since the film is treated at the high temperature.    [Patent Document 1] Japanese Patent O.P.I. Publication No. 2002-71957    [Patent Document 2] Japanese Patent O.P.I. Publication No. 2002-62430    [Patent Document 3] Japanese Patent O.P.I. Publication No. 2001-249223    [Patent Document 4] Japanese Patent O.P.I. Publication No. 2002-82226    [Patent Document 5] Japanese Patent O.P.I. Publication No. 2002-98832    [Patent Document 6] Japanese Patent O.P.I. Publication No. 2004-4474